I have a 99 sunfire with 2.2 and 3 speed auto. I keep gettin code P1870. The trans is shifting absolutly great, but the torque converter doesnt seem to stay locked in well. I can be going up a hill and the RPM's will come up as if its slipping. On flat ground its fine though. If I give it enough gas it will unlock so I know its locked when its slipping.

I read somewere this might be from the TCC solinoid?

anyone????
I noticed it does it worse at higher speeds, it doesnt even seem to lock up at highway speeds.
Also its worse when the trans is hot.

P1870 is Torque Converter Cltch slippage. When this DTC is tripped, the TCC releases, The PCM thinks the TCC is slipping and to keep from burning it up, it releases the TCC. This is a common fault with gear changes(or tranny swaps) to a lower gear ratio. The PCM compares the RPM to the MPH to check for TCC slippage, using a lower gear ratio causes you to turn more RPMs to get the same speed as the stock gear ratio would turn. The PCM sees this as the TCC is slipping and throws the DTC and disconnects the TCC.

The reason it occurs more often at highway speeds, is because you are at a steady state cruse and it will run a comparison test, which it will fail. The test will only be performed, if certain conditions are met. One condition being the motor is running at normal operating tempratures for a specified amount of time and at crusing speeds/RPMs. The PCM won't allow the TCC to engage, if the fault is present, in attempt to protect the transmission.

Well the car is completly stock.
I cleared the code and it was fine untill it reached operating temp.
Im getting lost on this now, maybe the PCM is bad?
Its really bugging me, getting worse mileage and I dont wanna melt the converter clutch.

last try?